The invention relates generally to methods and associated apparatus for controllably delivering radioactive or cytotoxic fluids for medical application, and specifically to methods and associated apparatus for the infusion of radioactive fluids for medical application, such as a liquid containing a radioisotope or biologically active substance.
In many medical applications it is necessary or desirable to administer amounts of radioactive fluids or medicines and other pharmaceutical fluids to a patient's body. For example, I-131 is administered to a patient in need of radiotherapy or I-125 for diagnostics. Other medicines that may be administered include radiosensitizers, chemotherapy, biologically active substances, and cytotoxics.
Certain of these applications involve infusing the fluid directly into a patient, such as through an intravenous tube or through direct application of the fluid to a specific portion of the patient's anatomy needing treatment or being subject to diagnostic procedures. Other medical applications involve infusing the fluid to a medical device located within or in proximity to the patient. An example of this type of application is illustrated in Williams U.S. Pat. No. 5,611,767. Williams shows an implantable balloon that can be filled with radioactive, chemotherapeutic or other fluids for treatment of marginal cancerous tissue remaining after surgical resection of a cancerous tumor. As further illustrated in Williams, fluids may be infused into the device, for example, by hypodermic syringe (FIG. 4 of U.S. Pat. No. 5,611,767) or by a transdermal catheter (FIG. 8 of U.S. Pat. No. 5,611,767). Even where a transdermal catheter is used, a hypodermic syringe is typically used to infuse the required fluid through the catheter.
Particularly in the case of radioactive fluid syringe injections, current methods of syringe shielding may not provide the patient or the medical practitioner with the total protection needed in terms of radiation shielding or containment of a spill or leak of the infusion system apparatus. Radioactive fluids are typically supplied to a balloon such as those illustrated in Williams, for a specified period of time. The fluid is then removed from the balloon and the balloon can be flushed with saline or some other non-hazardous dilutant before further surgery to remove the balloon from the patient's body. The infusion, removal and flushing of the radioactive fluid results in the use of several syringes which must be interchanged in the infusion system with a resulting increase in the possibility that radioactive fluids will leak or spill.
Syringe shields are currently available and are generally made to shield a syringe filled with radioactive fluids by employing lead (Pb) as a means of shielding the radioactivity. These devices, however, generally protect patients and medical personnel only from radioactive fluids within the body of the syringe, but do not provide adequate shielding and containment of possible leaks or spills of the infusion system.